Allow reset-state on attach and migration fields

The reset-state API call only sets that main status
column on the volume object.  There's also a method
to set attach status, however it turns out that due
to the implementation of the status validation method
in the parent class, this was impossible to use because
it only checked and accepted "status" NOT "attach_status".

This patch fixes that attach_status problem, it also implements
the ability to update the migration status.  A cinderclient change
will be needed to expose these calls as well.

DocImpact

Change-Id: I59e1bb2522f033c944fa07acf4876ca71c8c3d3f
Closes-Bug: #1308253
Merge "Allow reset-state on attach and migration fields"